Radio frequency identification (RFID) utilizes small tags, each containing electronics and an antenna that are capable of broadcasting a radio signal that identifies the tag. Such RFID tags can be active or passive. An active RFID tag includes a battery that allows the tag to periodically generate the radio signal. A passive RFID tag does not include an internal battery but instead is powered by an interrogator signal received by the tag's antenna. The power provided by the interrogator signal can be used immediately by the tag to provide a response signal or can be stored in a capacitor in the tag to be used later.
The radio signals generated by RFID tags are received and decoded by RFID readers. The RFID reader decodes the signal it receives to produce an identifier of the RFID tag found in the signal. Some RFID readers are also able to determine the strength of the radio signal received from the RFID tag. In such readers, the strength of the signal can be provided as an output known as a Received Signal Strength Indicator (RSSI).
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all disadvantages noted in the background.